JPS58152691A - Stern configuration for small ship - Google Patents

Abstract

PURPOSE:To cut water favorably when streaming ahead and reduce resistance at the time of steaming astern, by a method wherein both side parts of a transom except a fitting part for an outboard engine or the like are projected astern, and the lower surfaces of the projected parts are slanted backwards and sidewards. CONSTITUTION:A transom part of a small ship is constituted of a lower transom 2 and an upper transom 3, the both side parts 4 of the transom except a central part for fitting the outboard engine or the like are projected astern, and the lower surfaces of the projected parts are made to be slanted surfaces 5 facing backwards and sidewards. When the ship advances at a predetermined speed, water is cut at the lower end of the lower transom 2, thereby reducing resistance to propulsion. When steaming astern, water is released downwards and sidewards by the slanted surfaces 5 of the projected parts, so that the resistance can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the shape of the stern of a small boat.

BACKGROUND ART Conventionally, in a small boat mainly powered by an outboard motor or an inboard/outboard motor, the stern end of a small boat has a substantially single-plane transom formed substantially vertically for drainage during sailing.

With this structure, the transom creates a large propulsion resistance when reversing. If the transom is tilted significantly in order to reduce this resistance, the drainage performance will be hindered and the installation of the main engine will also be hindered.

The present invention has been made to overcome these conventional drawbacks, and is designed to ensure that water drains well when moving forward, and does not generate large propulsion resistance when moving backward. That is, in the transom portion of the present invention,
The hull on both sides except for the main engine attachment part is made to protrude rearward except for the bottom part, and the lower surface of this protrusion is an inclined surface facing rearward.

Embodiments of the present invention will be described below with reference to the drawings. A lower transom 2 is continuous to the rear end of the bottom plate 1, and an upper transom 3 is continuous to the upper part of the lower transom 2. The lower transom 2 is inclined significantly rearward, and the upper transom 3 is inclined almost vertically. An outboard motor or an inboard/outboard motor (not shown) is attached to the upper transom 3. Further, on both sides of this attachment part, a projecting part 4 is formed so that the hull projects rearward, except for the bottom part. The rear surface of this protrusion 4 is inclined rearward, and the lower surface 5 is an inclined surface facing rearward. Both side portions of the large protruding portion 4 are curved surfaces 10 with a large radius of curvature. 7 is a boat, thread material attached to the bottom, and 8 is a motorfell.

In the above configuration, when the ship is stopped, the water line 13 in Figure 1
As shown, the water surface is below the lower transom 2 and the protrusion 4.
When the ship is traveling at a predetermined speed, water is drained at the lower end of the lower transom 2 as shown by the water line 11, thereby reducing propulsion resistance. Further, when the vehicle moves backward, water hits the lower transom 2 and the protruding lower surface 5, but the water is released downward by the lower surface 5, so that no large propulsion resistance occurs. The reason why the lower surface 5 is inclined slightly toward the ship's side is to further reduce resistance by letting water escape to the side force when moving astern.

Furthermore, the lower transom 2 is also tilted significantly rearward to reduce water resistance. If the transom is formed on a single surface, it will be tilted a lot due to constraints on the main engine's storage space. Although it cannot be made positive, if the transom is formed into two stages, upper and lower, as shown in the figure, and the main engine is attached only to the upper transom 3, the lower transom 2 can be tilted significantly. The larger this inclination is, the better it is for reducing the resistance when traveling backwards, but if the slope is too large, water will not be drained when moving forward, so it should be set as large as possible so that water can be drained when moving forward. The limit to which water can be drained varies depending on the ship's speed, the shape of the lower end of the transom, etc.
It is sufficient to determine the slope of

In addition, as shown in FIG. 2, since curved surfaces 10 are formed on both sides 1 of the rear end, water that hits the rear surface 6 when traveling backward is released to the sides, thereby achieving the effect of reducing resistance. It can also move smoothly between obstacles at sea, such as seaweed farms.

As explained above, in this invention, protrusions are formed on both sides of the transom and the lower surface thereof is sloped, and this makes it possible to drain water during turns and reduce propulsion resistance when moving backwards. It is possible.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of the center of the stern section showing an embodiment of the present invention;
FIG. 2 is a plan view thereof, and FIG. 3 is a perspective view from below the stern. 1...bottom plate, 2...'F section transom, 3...
Upper transom, 4... protrusion, 5... lower surface. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Etsu Kotani Figure 1 Figure 2 Figure 1

Claims (1)

[Claims] 1. A stern shape of a small boat, characterized in that in the transom part, the hull on both sides excluding the main engine attachment part protrudes rearward except for the bottom part, and the lower surface of this protrusion is an inclined surface facing rearward.